title: Effects of cryopreservation on microbial-contaminated cord blood.
abstract: BACKGROUND
  Cord blood units (CBUs) are associated with significant risk of exposure to microbial contamination during collection and processing; however, the survival of bacteria within a CBU is poorly understood. This study aimed to determine whether contaminating organisms in CBU survive the cryopreservation, frozen storage, and subsequent thawing conditions before infusion.
  
  
  METHODS
  A total of 134 CBUs rejected from banking due to known contamination were thawed and rescreened using blood culture bottles (BacT/ALERT, bioMérieux). An additional 61 fresh CBUs were deliberately spiked with a range of microbial organisms and evaluated both before freeze and after thaw.
  
  
  RESULTS
  Microbial contaminants were detected after thaw in 63% of stored contaminated CBUs and 85% of spiked CBUs. Postthaw organism detection in spiked cord blood (CB) was higher in adult culture bottles (80%) than pediatric culture bottles (61%). Twenty percent of spiked organisms, particularly Bacillus subtilis, Escherichia coli, Clostridium sporogenes, and Propionibacterium acnes, were not detected in prefreeze samples but were detectable after thaw.
  
  
  CONCLUSIONS
  This study demonstrates that the majority of contaminating organisms isolated in a prefreeze sample of CB have the ability to survive cryopreservation, frozen storage, and thawing. Further, CBUs reported as microbial free may contain microbial contamination, which could result in transplantation of contaminated CB and be potentially deleterious to a patient.
authors.affiliation: Sydney Cord Blood Bank, Sydney Children's Hospital, Randwick, NSW, Australia; University of New South Wales, Sydney, NSW, Australia; BMT Laboratory, SEALS, Prince of Wales Hospital, Randwick, NSW, Australia; Division of Microbiology, SydPath, St. Vincent's Hospital, Darlinghurst, NSW, Australia.
authors.forename: Pamela
authors.initials: P
authors.lastname: Clark
authors.forename: Annette
authors.initials: A
authors.lastname: Trickett
authors.forename: Sandra
authors.initials: S
authors.lastname: Saffo
authors.forename: Damien
authors.initials: D
authors.lastname: Stark
mesh_terms: D001771:Blood Banks / Q000592:standards*; D015925:Cryopreservation; D005312:Fetal Blood / Q000382:microbiology*; D006801:Humans